I have 3 classes Player, Manager and Person. Person is the base class, Player and Manager extend Person and add specific properties to each.
I have also 3 tables sm_player, sm_manager and sm_person:

-------------------------------
sm_player / sm_manager
-------------------------------
id int PK
personId int FK to sm_person.id
....
-------------------------------

My mapping looks like:

<class name="Player" table="sm_player" lazy="false">
<id name="Id" column="id" type="Int32">
<generator class="identity"/>
</id>
...
<join table="sm_person" optional="true">
<key column="personId"/>
<property name="FirstName" column="firstName"/>
<property name="LastName" column="lastName"/>
...
</join>
</class>

Class Manager's mapping looks almost the same as Player.
My question is, do I need to specify a <generator> for <key> ? How does NHibernate know to generate a new sm_person.id when doing:

session.Save(player);

I am getting an error of course because I have not assigned personId. Do I have to save the player as a person first? Then how do I assign the personId if there is no property defined for it. I get the exact same result if I change from using <join> to using a class mapping definition for Person and sublasses for Player and Manager.
Please help.

Thanks.

Miguel.

OK, maybe I missunderstood the meaning of <join> <key>. I was getting this error:

NHibernate.Exceptions.GenericADOException: could not insert: [CuriMSI.SportsManager.Framework.Model.Player][SQL: INSERT INTO sm_player (throwsBats, number, height, weight, statusId) VALUES (?, ?, ?, ?, ?)] ---> MySql.Data.MySqlClient.MySqlException: Field 'personId' doesn't have a default value.

I removed the "not null" requirement on sm_player.personId and got pass that error to this one:

NHibernate.Exceptions.GenericADOException: could not insert: [CuriMSI.SportsManager.Framework.Model.Player#1][SQL: INSERT INTO sm_person (firstName, lastName, middleName, nickName, maidenName, cityOfBirth, dateOfBirth, avatarURL, biography, memberId, personId) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)] ---> MySql.Data.MySqlClient.MySqlException: Unknown column 'personId' in 'field list'.

So instead of sm_player.personId, NHibernate thinks that I am defining sm_person.personId. How do I tell NHibernate that the join is from sm_player to sm_person and not the opposite?

OK, inverse="true" on the join appears to have done the trick but now I am having another problem apparently from the join itself:

System.InvalidCastException: Unable to cast object of type 'System.Int32' to type 'CuriMSI.SportsManager.Framework.Model.Player'..

The NHibernate logs don't show any errors and there is no inner exceptions to see where exactly this cast occurs. I am guessing comes from Contacts relationship to person in the following mapping:

<class name="Player" table="sm_player" lazy="false">
<id name="Id" column="id" type="Int32">
<generator class="identity"/>
</id>
...
<join table="sm_person" inverse="true">
<key column="personId"/>
...
<bag name="Contacts" cascade="all" lazy="false">
<key column="personId" />
<many-to-many class="Contact"/>
</bag>
</join>
</class>

<class name="Contact" table="sm_contact" lazy="false">
<id name="Id" column="id" type="Int32">
<generator class="identity"/>
</id>
<property name="Label" column="label"/>
<property name="Value" column="value"/>
<many-to-one name="Type" class="ContactType" column="type"/>
</class>

My Player class is:

class Player : Person
{}

class Person
{
IList<Contact> Contacts { get; set; }
}

What is wrong with my mapping?
By the way I had to remove all "not null" constraint on all foreign keys referenced in my bag and join associations or the "default value not specified" error would show up.

Hello!!! .. anyone there?

OK, figured it all out.. :).
I was expecting session.Save() to return the object instead of just the id.
Problem solved and everything seems to work as it should.
Thanks to myself for helping.. myself.. fix the issue..:).